CHANCE® Helical Underpinning

Foundation subsidence issues in the UK requiring underpinning technology continue to be prevalent and an important expenditure for insurance companies and loss adjusters. Given the age of the building stock, varying geology, proximity to tree roots and extreme summer droughts, more and more structures are shifting causing cracks to appear and walls to buckle. CHANCE Helical Piles are renowned the world over for their ability to permanently fix subsidence issues on residential and commercial buildings and also to increase load capacities of existing structures.

CHANCE Underpinning & Helical pull-down micropile systems are used to transfer the building weight to bearing plates installed deep below ground in stable soil. For exterior remediation, underpinning brackets fixed to the foundation support the load of the structure and transfer that to the helical screw pile. When interior remediation is required, CHANCE interior slab bracket is the preferred solution. This patented system brings an economical solution to underpinning systems. Fast, predictable, and measurable are just some of the advantages of this Uk building control evaluated and pre-approved system (LABC).

In a Chance underpinning foundation, piles are installed independent of the structure to depths beyond problematic soils. The required load capacity is achieved through the measurement of the installation torque applied to the drive motor. The piles are attached to the existing foundation with an appropriately sized pre-engineered bracket.

How It Works

Our Chance certified and trained installers offer this technically superior and cost-effective Chance underpinning system throughout the UK as an alternative to more disruptive, expensive and time-consuming methods of stabilisation that require extensive excavations. The Chance installers use an engineered design backed by PI insurance which is tailored to the exact repair requirements and ground conditions onsite. The Chance underpinning method takes a matter of days as opposed to weeks with historic methods. Once the design is produced by a chartered structural engineer, minimal excavations down to the foundation is carried out, a notch is cut to support the pile bracket which will connect the helical pile to the foundation. The unique helical pile is then ‘screwed’ into the ground by a 2 person team either with handheld equipment or on a small mini digger. The helical pile is installed until the torque measurements confirm that the helical plates have reached competent load-bearing stratum. Adjustable ‘L’ shaped brackets are fitted to the installed helical pile fitting under and bolting onto the side of the foundation. the bracket is then jacked up to achieve the correct loading and or to revelvel the foudation preventing further settlement and transferring the weight of the building to the piles.

Uk Examples

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Underpinning Bracket Performance

Bracket Catalog No

C150-0121

C150-0298

C150-0299

Anchor Shaft Size

38mm Square Shaft

38mm Square Shaft

46mm Square Shaft

SS Anchor Series

Tensile Strength SS5

High tensile Strength SS150

Tensile Strength SS175

Minimum Bracket Ultimate Strength

178 kN

178 kN

356 kN

With 2.0 Safety Factor

89 kN

89 kN

178 kN

Typical Achievable Installed Capacity*

89 kN

111 kN

133 kN

*The exact capacity of CHANCE Helical Pile Foundations is a function of many individual elements, including the capacity of the foundation, bracket, anchor shaft, helix plate and bearing ground conditions, as well as the strength of the foundation-to-bracket connection and the quality of anchor installation. The last row of the table shows typical capacities of the CHANCE Helical Pier Foundation Systems that are achievable under normal conditions. Achievable capacities could be higher or lower depending on the above factors.